This invention relates to an enclosed gap-less lightning arrester device utilizing resistors having the excellent nonlinear characteristic, and more paticularly to an arrangement of such resistors improving a potential profile thereon.
The lightning arrester device utilized in miniature substations or the like established in narrow sites is required to be small-sized and is usually of the gas insulating type employing an electrically insulating gas such as sulfur hexafluoride (SF.sub.6). Conventional lightning arrester devices of the type referred to have comprised the grounded housing filled with sulfur hexafluoride, and a plurality of nonlinear characteristic elements of silicon carbide (SiC) alternating series discharge gaps within the housing and serially connected to the latter across an associated bus bar and the grounded housing. Also there are known lightning arrester devices of the type referred to employing sintered zinc oxide as the nonlinear characteristic element with the series discharge gaps omitted. In either case, the number of the nonlinear characteristic elements has been determined by an associated bus voltage. As a result, an increase in bus voltage has resulted in the necessity of increasing the dimension of the nonlinear characteristic elements and accordingly rendering the grounded housing large-sized, which is disadvantageous.
In addition, those lightning arrester devices have included the relatively narrow spacing between the grounded housing and a high voltage member disposed within the housing. However, when a high voltage such as a line-to-ground voltage is applied to the device through an equipment adjacent to such a grounded surface, the resulting electric field is adversely affected to form an uneven potential profile on the serially connected nonlinear characteristic elements. This uneven potential profile has thermally affected the performance of the lightning arrester devices.
It is an object of the present invention to provide a new and improved lightning arrester device including nonlinear characteristic elements formed of an electrically resisting material having the excellent nonlinear characteristic and small-sized to be suitable for use in a miniature substation or the like.
It is another object of the present invention to provide a new and improved enclosed lightning arrester device having a potential profile on an assembly of serially connected nonlinear resistors as uniform as possible.